“From Dallas, Texas. . . . ” The haggard newsman has just been handed wire copy. He removes his glasses. He looks into the camera and gives us the first hard news that our young president will never grow old. He marks the time of death on the newsroom clock and holds a moment of silence.

This was Walter Cronkite on Nov. 22, 1963, announcing the death of John F. Kennedy.

It was consummate Cronkite — unscripted, authentic and heartfelt. For 19 years, the anchor of “The CBS Evening News” shared in our public grief and celebration. He was one of us, and Douglas Brinkley’s “Cronkite” is a majestic biography of America’s greatest and most beloved broadcast journalist.

“He was reassuringly permanent when so much was in flux,” writes Brinkley, a historian and contributing editor at Vanity Fair. “Even when he was announcing tragic news, he was himself a reminder that America would persevere.”

Perseverance was the hallmark of Cronkite’s surprisingly choppy career. He was buoyed by his ability to connect with an audience, a connection never more apparent than during CBS’s marathon coverage of the Kennedy assassination. Seventy million Americans and viewers in 23 countries tuned in. “CBS News became the meeting hall, the cathedral, the corner bar and the town square — wherever people went when they wanted the healing comfort of a group,” Brinkley writes, and Cronkite was the “impresario” of mourning, the unofficial national grief counselor.

Cronkite never shied away from telling hard truths. Recall his half-hour “Report From Vietnam” on Feb. 27, 1968, in which he declared the Vietnam War a “stalemate.” It was a verdict the veteran war correspondent didn’t relish delivering, but Cronkite, who had recently returned from reporting on the Tet offensive, now believed that the war was unwinnable and indefensible. He felt “conned” by Lyndon Johnson, Brinkley writes, and “sickened” that his network had swallowed the Pentagon’s spin.

How did Cronkite get the credentials to be taken at his word that an American war could not be won?

Born in 1916 in St. Joseph, Mo., Cronkite dreamed of becoming a broadcaster. An indifferent student, he dropped out of the University of Texas after two years and entered the newspaper business, covering the nightclub and church beats for The Houston Press.

At 19, he got his first radio job at Kansas City’s KCMO station, broadcasting college football games under the name Walter Wilcox (Cronkite sounded too German). He read the plays off the wire ticker, then re-enacted them for the audience as if he were at the game. “I didn’t need any facts,” he said. “I just used my imagination.”

Cronkite’s KCMO years were notable for two events: He met and married Mary Elizabeth Maxwell, known as Betsy, a KCMO advertising copywriter, and he was abruptly fired. He refused to report on a fire at city hall in which three firefighters had supposedly died. He defied his boss, insisting upon getting a second source before going on air. It was the standard that mattered: get the story right and then, first.

He landed on his feet as a night editor at United Press. It was “his proving ground,” Brinkley writes, the job that formed Cronkite as a journalist. He did everything from fact-checking to reporting, and in 1943 he covered the American bombing campaign over Germany. He joined a cadre of correspondents including Andy Rooney; they called themselves the “Writing Sixty-Ninth,” and they were instructed by Hugh Baillie, president of U.P., to “get the smell of warm blood into their copy.”

Here is Cronkite’s report from a raid he accompanied over Germany: “American Flying Fortresses have just come back from an assignment to hell — a hell of 26,000 feet above the earth, a hell of burning tracer bullets and bursting gunfire, of crippled Fortresses and burning German fighter planes, of parachuting men and others not so lucky.”

This dispatch caught the attention of Edward R. Murrow, the legendary CBS broadcaster, who offered him a CBS Radio job based in Stalingrad. Cronkite accepted — only to turn it down. “Radio was the new print,” Brinkley writes, but the U.P. man stayed loyal to wire reporting.

Cronkite’s work during the war informed the rest of his career. As Bob Schieffer said on a “Face the Nation” program honoring Cronkite, it’s why Americans trusted him. “Everybody knew that Walter didn’t get his suntan in the studio lights.”

Cronkite was finally recruited by Murrow to cover the Korean War. He tried his hand at television news and, according to Brinkley, exhibited an almost “innate understanding of the medium.” From 1953 to 1957, Cronkite was the host of “You Are There,” a weekly program on which he pretended to be a news reporter covering a major historical event like the Boston Tea Party (and offering covert critiques of McCarthyism), but his career continued to be rocky. In 1954, he was hired and promptly fired as host of “The Morning Show”; later, he was passed over for “Face the Nation,” which the network was creating to rival NBC’s “Meet the Press.”

Cronkite’s coverage of the 1964 Republican convention was judged so verbose and lackluster that the CBS chairman William Paley yanked him. The veteran Robert Trout and a young Roger Mudd were brought in to co-anchor the Democratic convention.

By the 1968 Chicago conventions, however, Cronkite was riding high again. “The Evening News” was tops in the ratings, its anchorman sure of his position and his material. His “Report From Vietnam” had won him widespread respect, and he was at his best as he held the peace as the convention devolved into violence. I remember Cronkite ending one late-night session bidding viewers to “get some sleep,” telling us he’d “see us in the morning.” It was gavel-to-gavel coverage, and he knew we were staying with him.

But Brinkley also reveals Cronkite’s darker, competitive side. He was churlish to colleagues and hated sharing the spotlight. He was so outraged to be co-­anchoring the 1960 convention with Edward R. Murrow that he locked himself in the anchor booth and refused to come out for photos. When Barbara Walters was paired with Harry Reasoner to anchor at ABC, Cronkite was publicly polite, but according to Brinkley, he “privately hoped she’d fail.” This was not news to her. “Let’s just say Uncle Walter wasn’t Uncle Walter to me,” she said. Tom Brokaw agreed: “He was very protective of his seat of power. This nicest-guy-in-the-world was more Darwinian than you could imagine when it came to being top dog.” Cronkite’s ruthlessness was never more in evidence than during the 1952 Chicago conventions. Competition for coverage was fierce, and Cronkite (with the approval of CBS) had the Republican credentials committee room bugged.

Cronkite didn’t want to lose. Nor did he like the idea of giving up the anchor desk, even to Dan Rather, his preferred successor. His last night anchoring “The CBS Evening News” was March 6, 1981, but he was not prepared for retirement. “He had quit too soon,” Brinkley writes. “He had never felt more hopeless. He had a partial interest in everything, without a sharp sense of mission about any one thing.”

It’s time for the elephant in the room. Was Cronkite a liberal?

The left-leaning was right there, Brink­ley notes, for all to hear if not see: Cronkite was always more outspoken off camera. “I thought that some day the roof was going to fall in,” Cronkite said. “Somebody was going to write a big piece in the newspaper or something. I don’t know why to this day I got away with it.” At a dinner honoring the Texas representative Barbara Jordan, he said of the Democratic losses in the 1988 election:

“Liberalism isn’t dead in this country. It isn’t even comatose. It simply is suffering a severe case of acute laryngitis. It simply has temporarily — we hope — lost its voice. . . . But God Almighty, God Almighty, we’ve got to shout these truths in which we believe from the rooftops, like that scene in the movie ‘Network.’ We’ve got to throw open our windows and shout these truths to the streets and to the ­heavens.”

It was “Cronkite’s political coming-out party,” Brinkley writes. “The charade of being Mr. Center was over.” Curiously Cronkite’s liberal bent didn’t detract from his credibility or popularity. It seemed to me that conservatives watched him with great respect, distilling out whatever leftish sentiment they might detect.

But “Cronkite” will endure not for what it tells us about broadcast media but for what it reveals about the man — his paradoxes, his penchant for pranks and dirty jokes, his long and happy marriage.

“The greatest old master in the art of living that I know is Walter Cronkite,” Andy Rooney wrote in The Washington Post. “If life were fattening, Walter Cronkite would weigh 500 pounds.” We, his viewers, never got to go drinking with our guy. We knew him in a more formal setting, but our memories feel just as intimate. I remember as a young boy watching “You Are There” in wonderment as he grilled the violators of King Tut’s tomb. I remember rushing to my college dormitory to watch him deliver the deadly news from Dallas. I remember as a graduate student walking in fall and winter evenings to the student union to catch him and Eric Sevareid evoke the excitement of the elections.

In 1980, Cronkite, the college dropout, received an honorary doctorate from Harvard and with it a standing ovation. Fred Friendly, a former president of CBS News, told him that he wasn’t being honored merely for his work on television.

“At a time when everybody was lying — fathers, mothers, teachers, presidents, governors, senators — you seemed to be telling the truth night after night. They didn’t like the truth, but they believed you at a time when they needed somebody to believe.”

“Cronkite” is evidence that a job can be done just about perfectly. That goes for the man and this exceptional biography.

CRONKITE

By Douglas Brinkley

Illustrated. 819 pp. Harper/HarperCollins Publishers. $34.99.

Chris Matthews is the host of “Hardball” on MSNBC and “The Chris Matthews Show” on NBC. His most recent book is “Jack Kennedy: Elusive Hero.”

A version of this review appears in print on July 8, 2012, on Page BR12 of the Sunday Book Review with the headline: And That’s the Way It Was. Today's Paper|Subscribe